Abstract: The free-cutting copper alloy according to the present invention contains a greatly reduced amount of lead in comparison with conventional free-cutting copper alloys, but provides industrially satisfactory machinability. The free-cutting alloys comprise 69 to 79 percent, by weight, of copper, 2.0 to 4.0 percent, by weight, of silicon, 0.02 to 0.4, by weight, of lead, and the remaining percent, by weight, of zinc.

Abstract: The free-cutting copper alloy according to the present invention contains a greatly reduced amount of lead in comparison with conventional free-cutting copper alloys, but provides industrially satisfactory machinability. The free-cutting alloys comprise 69 to 79 percent, by weight, of copper, 2.0 to 4.0 percent, by weight, of silicon, 0.02 to 0.4 percent, by weight, of lead, and the remaining percent, by weight, of zinc.

Abstract: The free-cutting copper alloy according to the present invention contains a greatly reduced amount of lead in comparison with conventional free-cutting copper alloys, but provides industrially satisfactory machinability. The free-cutting alloys comprise 69 to 79 percent, by weight, of copper, 2.0 to 4.0 percent, by weight, of silicon, 0.02 to 0.4, by weight, of lead, and the remaining percent, by weight, of zinc.

Abstract: The free-cutting copper alloy according to the present invention contains a greatly reduced amount of lead in comparison with conventional free-cutting copper alloys, but provides industrially satisfactory machinability. The free-cutting alloys comprise 69 to 79 percent, by weight, of copper, 2.0 to 4.0 percent, by weight, of silicon, 0.02 to 0.4, by weight, of lead, and the remaining percent, by weight, of zinc.

Abstract: A lead-free free-cutting copper alloy having 69 to 79 percent, by weight, of copper; greater than 3 percent, by weight, of silicon; and a remaining percent, by weight, of zinc. The alloy preferable has greater than 3.0 percent and less than or equal to 4.0 percent, by weight, of silicon; and at least one element selected from among 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium. The alloy also preferable has at least one element selected from among 0.3 to 3.5 percent, by weight, of tin, 1.0 to 3.5 percent, by weight, of aluminum, and 0.02 to 0.25 percent, by weight, of phosphorus. In further embodiments, the alloy has at least one element selected from among 0.02 to 0.15 percent, by weight, of antimony, and 0.02 to 0.15 percent, by weight, of arsenic.

Abstract: A lead-free free-cutting copper alloy having 69 to 79 percent, by weight, of copper; greater than 3 percent, by weight, of silicon; and a remaining percent, by weight, of zinc. The alloy preferable has greater than 3.0 percent and less than or equal to 4.0 percent, by weight, of silicon; and at least one element selected from among 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium. The alloy also preferable has at least one element selected from among 0.3 to 3.5 percent, by weight, of tin, 1.0 to 3.5 percent, by weight, of aluminum, and 0.02 to 0.25 percent, by weight, of phosphorus. In further embodiments, the alloy has at least one element selected from among 0.02 to 0.15 percent, by weight, of antimony, and 0.02 to 0.15 percent, by weight, of arsenic.

Abstract: An artificially patinated copper plate in which a copper sulfide layer 2 is formed on the surface of a copper base plate 1 by sulfiding for coating the same, and the copper sulfide layer 2 having an artificially patinated layer 3 is formed distributed and bonded thereon by spraying a resin solution mixed with basic copper carbonate constituting the main component of natural patina. The percentage of the area occupied by the artificially patinated layer 3 on the copper sulfide layer 2 is most preferably 25% to 80% and the thickness of the copper sulfide layer 2 is most preferably 0.1 to 0.5 .mu.m.